First, makes a tiger shape, and then
throws-in to make a ko.
Note that this ko is fairly heavy for White, although conventional wisdom tells us that the ko is heavier for Black. The reason is that if White loses the ko, the loss is quite substantial.
If prevents the ko, then
destroys the eye and kills.
The descent at fails. The cut at
is tesuji, and Black gains sente to live at
. Now White cannot approach at a and capture the three Black stones.
here is useless.
The connection at fails. After
makes the second eye, White is unable to play at a, so Black wins the capturing race at the top.
captures the stone at the corner and lives.